Functional requirements to select plastic products

To fully understand the use environment and actual use requirements of plastic parts, the following aspects should be considered.

① Whether the mechanical properties of plastics, such as strength, rigidity, toughness, elasticity, bending properties, impact properties, and sensitivity to stress, meet the requirements for use.

②Physical properties of plastics, such as adaptability to temperature changes in the use environment, optical properties, degree of heat or electrical insulation, finishing and appearance, etc., meet the requirements for use.

③ The chemical properties of plastics, such as resistance to contact (water, solvent, oil, medicine) and safety in use, etc., meet the requirements for use.

When selecting materials based on material performance data, there are obvious differences between plastics and metals. For metals, their performance data can basically be used for material screening and product design. But it is not the same for plastics with viscoelasticity. Various test standards and documented polymer performance data are measured under many specific conditions, usually under short-term force or specified temperature or low strain rate. The conditions may be quite different from the actual working conditions, especially not suitable for predicting the use strength and resistance to temperature rise of plastics. When citing performance data for all plastic materials, we must pay attention to whether they are consistent with the use conditions and use environment. All cited data should be converted into engineering performance data related to actual performance, and materials should be selected according to the required performance.